Well, there are companies on the market (Courtesy Aircraft, Provenance Fighter) building their business around buying and selling warbirds. They do it for profit. Otherwise they wouldn’t be relevant. My investment would be mainly about love but there should be some economy in it as well. A warbird can cost several millions. I doubt there is anybody on this planet spending so much money just for love if there are companies like Courtesy and Provenance. I see the warbird market similar to that of fine art. Everybody knows the value increases in years. If data I am trying to get are available there would be much more investors and more money for restoration, operation and preservation for those beautiful species.
There are guys on this forum able to recognize the precise airplane from unclear old pictures. They are able to tell who and where flew and owned the airplane. I just thought they would be able to remember some finances around it as well. Example: Mark and Ray Hanna bought their Spitfire (type, number…) in 1993 for £300.000.
Anyway many thanks for any response.